1. Field of the Disclosure
This disclosure relates in general to an image forming apparatus, such as a printer, and more particularly, to an image forming apparatus employing an improved approach to measuring side 1 to side 2 image misregistration.
2. Description of Related Art
Printers provide fast, reliable, and automatic reproduction of images. The word “printer” as used herein encompasses any apparatus, such as a digital copier, book marking machine, facsimile machine, multi-function machine, etc., which performs a print outputting function for any purpose. Printing features that may be implemented in printers include the ability to do either full color or black and white printing, and printing onto one (simplex) or both sides of the image substrate (duplex). The image substrate can be either cut sheet or web fed.
Color misregistration has been addressed in the past. For example, a system and method for detecting and correcting color misregistration errors in a color image forming device is shown in U.S. Patent Application Publication No. U.S. 2005/0157317 A1, now abandoned. Spectrophotometric analysis is performed on special color registration patches to transform color registration errors into a color signal. The color registration patch is designed so the color shift detected by the spectrophotometer allows prediction of the amount of color misregistration. In U.S. Patent Application Publication No. U.S. 2008/0030788 A1, now U.S. Pat. No. 8,274,717, a system and method is provided for characterizing color separation misregistration associated with marking a substrate. The method includes providing an input image having a plurality of patches, each patch having a pattern using a first and second color; marking a substrate with a copy of the input image suing a first and second color separation to correspond to the first and second colors, respectively; and measuring a color characteristic of marking of respective copied patches of the copied plurality of patches and generating corresponding colorimetric values. Misregistration of the first color separation markings relative to the second color separation markings is characterized based on the measured colorimetric values. A method for using image show-through for measuring front and back image registration that relies on a full width array sensor and printed registration marks is shown in U.S. Patent Application Publication No. U.S. 2010/0329756, now allowed. All of the heretofore mentioned references, and their references, are included herein by reference.
While these heretofore mentioned color misregistration techniques have been useful, they do not address the problem encountered measuring Side 1 to Side 2 image on paper (IOP) misregistration. Current methods for measuring Side 1 to Side 2 IOP misregistration involve using an eye loupe, off-line scanner, or in-line scanner. A manual measurement is both time consuming and involves human error. A scanner solution is expensive and the image processing can be complicated.
Hence, there is still a need for a simple method that will allow one to easily measure Side 1 to Side 2 IOP misregistration.